In recent years, a liquid crystal display device having the following structure has been put into practical use. That is, a touch panel configured to enable a user to operate and input information by touching an image display surface with his/her finger or the like is externally mounted to a front surface side of a liquid crystal panel. Further, a structure of embedding a touch sensor function into the liquid crystal panel has also been proposed. The system of embedding the touch sensor function into the liquid crystal panel may be classified into an on-cell type and an in-cell type. In the on-cell type, a layer having a touch sensor function is formed between a polarizing plate and a glass substrate on which a color filter is formed of the liquid crystal panel. In the in-cell type, a touch sensor is formed in a thin film transistor (TFT) substrate of the liquid crystal panel during a manufacturing process for the substrate. Achieving the in-cell touch sensor function enables reduction in thickness and weight of the liquid crystal display device.
As a related-art liquid crystal display device having an in-cell touch sensor function embedded therein, there has been proposed a configuration in which, among pixel electrodes and a common electrode used for applying an electric field to liquid crystal, the common electrode doubles as a drive electrode of a capacitive touch sensor.